This invention relates generally to an absorbent article, and more particularly to improvements in scrim reinforced absorbent cores having reduced stiffness. The reinforced absorbent structure can be employed in absorbent articles, such as disposable diapers, children's training pants, feminine care articles, incontinence articles, bandages, and the like.
Absorbent articles typically include fluid absorbent structures or cores conventionally formed by air forming or air laying techniques, and are covered by an intake function liner and a barrier function liner. The manufacture of the absorbent core may begin by fiberizing a fibrous sheet of cellulose or other suitable absorbent material in a conventional fiberizer, or other shredding device, to form discrete fibers, and particles of superabsorbent material may be mixed with the discrete fibers. The fibers and superabsorbent particles are then entrained in an air stream and directed to and deposited on a foraminous forming surface to form an absorbent fibrous web. In addition, bonding agents or other strengthening components may be incorporated to provide a more stabilized web.
Other techniques have also been employed to form webs of stabilized absorbent material. Such techniques have included dry-forming techniques, foam-forming techniques, and various wet-laying and wet-forming techniques. The resulting webs of absorbent material have included fibers, natural fibers, synthetic fibers, superabsorbent materials, binders, and strengthening components in desired combinations. However formed, the absorbent web is then processed (e.g., cut into individual absorbent cores) and assembled with other components (intake and barrier layers) to produce a final absorbent article. Absorbent material webs have also been strengthened by adding reinforcing members on at least one side of the absorbent material webs. Such reinforcing members have included reinforcement filaments, tissue layers, fabric layers and netting materials. It is also known to add staple binder fibers to the absorbent materials upon formation of the absorbent material web. The binder fibers are activated by heat to produce adhesion of the absorbent materials.
Integrity of an absorbent core formed from such an absorbent material web is desirable to avoid bunching, clumping, cracking and separating of the absorbent core in either a wet or a dry state so as to improve the fit and comfort to the wearer of the absorbent article. Sagging and drooping of the absorbent article due to fluid insults can cause gaps between the article and the wearer's body which may lead to leaking. Poor integrity of the absorbent core results in absorbent cracking and separating in use which continues to be a common problem with conventional air-formed absorbent cores. The incorporation of a scrim reinforcement material internally into the structure of the absorbent core dramatically reduces this integrity problem. However, in some cases scrim reinforcement can also result in undesirable absorbent stiffness which adversely impacts conformability, fit and comfort, especially in the crotch region of the absorbent article. This is particularly relevant for a narrow crotch geometry, where the buckling span is shorter as compared to wide crotch executions.
As absorbent cores are made both thinner and narrower to achieve increased comfort (particularly in the crotch region), web stresses encountered in manufacture and use can be high, requiring better reinforcement. For instance in manufacture, tension on the absorbent core can be particularly high during start-up and shutdown of processing machinery, during removal from the forming surface, and during conveyance through component attachment and packaging machinery. In use, the lack of integrity can make the absorbent article fit poorly and impair product performance by breaking up the absorbent core, and thereby inhibiting fluid control, liquid handling and wicking which can contribute to leaking.
It is known to use a netting or scrim within the absorbent core which is connected to the fibrous absorbent material to hold the material together under loads. Conventional reinforcement scrims have exhibited shortcomings when employed to form desired absorbent structures and have not provided the desirable combinations of low cost, high strength and low irritation in addition to the basic attributes of comfort and high fluid absorption. For example, conventional reinforcement materials and formats have been relatively unstretchable and/or inflexible. Thus, an absorbent garment incorporating scrim may not readily conform to the wearer's body or give as the wearer moves or the absorbent core is loaded. As a result, it has been difficult to achieve an absorbent structure with desired stretchability and resistance to tears when exposed to the forces of movement and body exudates. Additionally, reinforcement scrims with widths suitable for the narrow crotch portion of the absorbent article have been used in the much wider waist portions of the article. As a result, it has been difficult to achieve an absorbent structure having the desired strength in the waist portions.